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|
/*
SSSD
Fail over helper functions.
Authors:
Martin Nagy <mnagy@redhat.com>
Copyright (C) Red Hat, Inc 2009
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <sys/time.h>
#include <errno.h>
#include <stdbool.h>
#include <strings.h>
#include <talloc.h>
#include "util/dlinklist.h"
#include "util/refcount.h"
#include "util/util.h"
#include "providers/fail_over.h"
#include "resolv/async_resolv.h"
#define STATUS_DIFF(p, now) ((now).tv_sec - (p)->last_status_change.tv_sec)
#define SERVER_NAME(s) ((s)->common ? (s)->common->name : "(no name)")
#define DEFAULT_PORT_STATUS PORT_NEUTRAL
#define DEFAULT_SERVER_STATUS SERVER_NAME_NOT_RESOLVED
struct fo_ctx {
struct fo_service *service_list;
struct server_common *server_common_list;
/* Settings. */
time_t retry_timeout;
};
struct fo_service {
struct fo_service *prev;
struct fo_service *next;
struct fo_ctx *ctx;
char *name;
struct fo_server *active_server;
struct fo_server *last_tried_server;
struct fo_server *server_list;
};
struct fo_server {
struct fo_server *prev;
struct fo_server *next;
void *user_data;
int port;
int port_status;
struct fo_service *service;
struct timeval last_status_change;
struct server_common *common;
};
struct server_common {
REFCOUNT_COMMON;
struct server_common *prev;
struct server_common *next;
char *name;
struct hostent *hostent;
struct resolve_service_request *request_list;
int server_status;
struct timeval last_status_change;
};
struct resolve_service_request {
struct resolve_service_request *prev;
struct resolve_service_request *next;
struct server_common *server_common;
struct tevent_req *req;
};
struct status {
int value;
struct timeval last_change;
};
struct fo_ctx *
fo_context_init(TALLOC_CTX *mem_ctx, time_t retry_timeout)
{
struct fo_ctx *ctx;
ctx = talloc_zero(mem_ctx, struct fo_ctx);
if (ctx == NULL) {
DEBUG(1, ("No memory\n"));
return NULL;
}
ctx->retry_timeout = retry_timeout;
DEBUG(3, ("Created new fail over context, retry timeout is %d\n",
retry_timeout));
return ctx;
}
static const char *
str_port_status(enum port_status status)
{
switch (status) {
case PORT_NEUTRAL:
return "neutral";
case PORT_WORKING:
return "working";
case PORT_NOT_WORKING:
return "not working";
}
return "unknown port status";
}
static const char *
str_server_status(enum server_status status)
{
switch (status) {
case SERVER_NAME_NOT_RESOLVED:
return "name not resolved";
case SERVER_RESOLVING_NAME:
return "resolving name";
case SERVER_NAME_RESOLVED:
return "name resolved";
case SERVER_WORKING:
return "working";
case SERVER_NOT_WORKING:
return "not working";
}
return "unknown server status";
}
/*
* This function will return the status of the server. If the status was
* last updated a long time ago, we will first reset the status.
*/
static enum server_status
get_server_status(struct fo_server *server)
{
struct timeval tv;
time_t timeout;
if (server->common == NULL)
return SERVER_NAME_RESOLVED;
DEBUG(7, ("Status of server '%s' is '%s'\n", SERVER_NAME(server),
str_server_status(server->common->server_status)));
timeout = server->service->ctx->retry_timeout;
if (timeout != 0 && server->common->server_status == SERVER_NOT_WORKING) {
gettimeofday(&tv, NULL);
if (STATUS_DIFF(server->common, tv) > timeout) {
DEBUG(4, ("Reseting the server status of '%s'\n",
SERVER_NAME(server)));
server->common->server_status = SERVER_NAME_NOT_RESOLVED;
server->last_status_change.tv_sec = 0;
}
}
return server->common->server_status;
}
/*
* This function will return the status of the service. If the status was
* last updated a long time ago, we will first reset the status.
*/
static enum port_status
get_port_status(struct fo_server *server)
{
struct timeval tv;
time_t timeout;
DEBUG(7, ("Port status of port %d for server '%s' is '%s'\n", server->port,
SERVER_NAME(server), str_port_status(server->port_status)));
timeout = server->service->ctx->retry_timeout;
if (timeout != 0 && server->port_status == PORT_NOT_WORKING) {
gettimeofday(&tv, NULL);
if (STATUS_DIFF(server, tv) > timeout) {
DEBUG(4, ("Reseting the status of port %d for server '%s'\n",
server->port, SERVER_NAME(server)));
server->port_status = PORT_NEUTRAL;
server->last_status_change.tv_sec = tv.tv_sec;
}
}
return server->port_status;
}
static int
server_works(struct fo_server *server)
{
if (get_server_status(server) == SERVER_NOT_WORKING)
return 0;
return 1;
}
static int
service_works(struct fo_server *server)
{
if (!server_works(server))
return 0;
if (get_port_status(server) == PORT_NOT_WORKING)
return 0;
return 1;
}
static int
service_destructor(struct fo_service *service)
{
DLIST_REMOVE(service->ctx->service_list, service);
return 0;
}
int
fo_new_service(struct fo_ctx *ctx, const char *name,
struct fo_service **_service)
{
struct fo_service *service;
int ret;
DEBUG(3, ("Creating new service '%s'\n", name));
ret = fo_get_service(ctx, name, &service);
if (ret == EOK) {
DEBUG(5, ("Service '%s' already exists\n", name));
if (_service) {
*_service = service;
}
return EEXIST;
} else if (ret != ENOENT) {
return ret;
}
service = talloc_zero(ctx, struct fo_service);
if (service == NULL)
return ENOMEM;
service->name = talloc_strdup(service, name);
if (service->name == NULL) {
talloc_free(service);
return ENOMEM;
}
service->ctx = ctx;
DLIST_ADD(ctx->service_list, service);
talloc_set_destructor(service, service_destructor);
if (_service) {
*_service = service;
}
return EOK;
}
int
fo_get_service(struct fo_ctx *ctx, const char *name,
struct fo_service **_service)
{
struct fo_service *service;
DLIST_FOR_EACH(service, ctx->service_list) {
if (!strcmp(name, service->name)) {
*_service = service;
return EOK;
}
}
return ENOENT;
}
static int
get_server_common(TALLOC_CTX *mem_ctx, struct fo_ctx *ctx, const char *name,
struct server_common **_common)
{
struct server_common *common;
DLIST_FOR_EACH(common, ctx->server_common_list) {
if (!strcmp(name, common->name)) {
*_common = rc_reference(mem_ctx, struct server_common, common);
if (_common == NULL)
return ENOMEM;
return EOK;
}
}
return ENOENT;
}
static struct server_common *
create_server_common(TALLOC_CTX *mem_ctx, struct fo_ctx *ctx, const char *name)
{
struct server_common *common;
common = rc_alloc(mem_ctx, struct server_common);
if (common == NULL)
return NULL;
common->name = talloc_strdup(common, name);
if (common->name == NULL) {
talloc_free(common);
return NULL;
}
common->prev = NULL;
common->next = NULL;
common->hostent = NULL;
common->request_list = NULL;
common->server_status = DEFAULT_SERVER_STATUS;
common->last_status_change.tv_sec = 0;
common->last_status_change.tv_usec = 0;
DLIST_ADD_END(ctx->server_common_list, common, struct server_common *);
return common;
}
int
fo_add_server(struct fo_service *service, const char *name, int port,
void *user_data)
{
struct fo_server *server;
int ret;
DEBUG(3, ("Adding new server '%s', to service '%s'\n",
name ? name : "(no name)", service->name));
DLIST_FOR_EACH(server, service->server_list) {
if (server->port != port || server->user_data != user_data)
continue;
if (name == NULL && server->common == NULL) {
return EEXIST;
} else if (name != NULL && server->common != NULL) {
if (!strcmp(name, server->common->name))
return EEXIST;
}
}
server = talloc_zero(service, struct fo_server);
if (server == NULL)
return ENOMEM;
server->port = port;
server->user_data = user_data;
server->service = service;
server->port_status = DEFAULT_PORT_STATUS;
if (name != NULL) {
ret = get_server_common(server, service->ctx, name, &server->common);
if (ret == ENOENT) {
server->common = create_server_common(server, service->ctx, name);
if (server->common == NULL) {
talloc_free(server);
return ENOMEM;
}
} else if (ret != EOK) {
talloc_free(server);
return ret;
}
}
DLIST_ADD_END(service->server_list, server, struct fo_server *);
return EOK;
}
static int
get_first_server_entity(struct fo_service *service, struct fo_server **_server)
{
struct fo_server *server;
/* If we already have a working server, use that one. */
server = service->active_server;
if (server != NULL) {
if (service_works(server)) {
goto done;
}
service->active_server = NULL;
}
/*
* Otherwise iterate through the server list.
*/
/* First, try servers after the last one we tried. */
if (service->last_tried_server != NULL) {
DLIST_FOR_EACH(server, service->last_tried_server->next) {
if (service_works(server)) {
goto done;
}
}
}
/* If none were found, try at the start. */
DLIST_FOR_EACH(server, service->server_list) {
if (service_works(server)) {
goto done;
}
if (server == service->last_tried_server) {
break;
}
}
service->last_tried_server = NULL;
return ENOENT;
done:
service->last_tried_server = server;
*_server = server;
return EOK;
}
static int
resolve_service_request_destructor(struct resolve_service_request *request)
{
DLIST_REMOVE(request->server_common->request_list, request);
return 0;
}
static int
set_lookup_hook(struct fo_server *server, struct tevent_req *req)
{
struct resolve_service_request *request;
request = talloc(req, struct resolve_service_request);
if (request == NULL) {
DEBUG(1, ("No memory\n"));
talloc_free(request);
return ENOMEM;
}
request->server_common = server->common;
request->req = req;
DLIST_ADD(server->common->request_list, request);
talloc_set_destructor(request, resolve_service_request_destructor);
return EOK;
}
/*******************************************************************
* Get server to connect to. *
*******************************************************************/
struct resolve_service_state {
struct fo_server *server;
};
static void fo_resolve_service_done(struct tevent_req *subreq);
struct tevent_req *
fo_resolve_service_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
struct resolv_ctx *resolv, struct fo_service *service)
{
int ret;
struct fo_server *server;
struct tevent_req *req;
struct tevent_req *subreq;
struct resolve_service_state *state;
DEBUG(4, ("Trying to resolve service '%s'\n", service->name));
req = tevent_req_create(mem_ctx, &state, struct resolve_service_state);
if (req == NULL)
return NULL;
ret = get_first_server_entity(service, &server);
if (ret != EOK) {
DEBUG(1, ("No available servers for service '%s'\n", service->name));
goto done;
}
state->server = server;
if (server->common == NULL) {
/* This server doesn't have a name, we don't do name resolution. */
tevent_req_done(req);
tevent_req_post(req, ev);
return req;
}
switch (get_server_status(server)) {
case SERVER_NAME_NOT_RESOLVED: /* Request name resolution. */
/* TODO: Enable IPv6. */
subreq = resolv_gethostbyname_send(server->common, ev, resolv,
server->common->name, AF_INET);
if (subreq == NULL) {
ret = ENOMEM;
goto done;
}
tevent_req_set_callback(subreq, fo_resolve_service_done, server->common);
fo_set_server_status(server, SERVER_RESOLVING_NAME);
/* FALLTHROUGH */
case SERVER_RESOLVING_NAME:
/* Name resolution is already under way. Just add ourselves into the
* waiting queue so we get notified after the operation is finished. */
ret = set_lookup_hook(server, req);
if (ret != EOK)
goto done;
break;
default: /* The name is already resolved. Return immediately. */
tevent_req_done(req);
tevent_req_post(req, ev);
break;
}
done:
if (ret != EOK) {
tevent_req_error(req, ret);
tevent_req_post(req, ev);
}
return req;
}
static void set_server_common_status(struct server_common *common,
enum server_status status);
static void
fo_resolve_service_done(struct tevent_req *subreq)
{
int resolv_status;
struct resolve_service_request *request;
struct server_common *common;
int ret;
common = tevent_req_callback_data(subreq, struct server_common);
if (common->hostent != NULL) {
talloc_zfree(common->hostent);
}
ret = resolv_gethostbyname_recv(subreq, common,
&resolv_status, NULL, &common->hostent);
talloc_free(subreq);
if (ret != EOK) {
DEBUG(1, ("Failed to resolve server '%s': %s\n", common->name,
resolv_strerror(resolv_status)));
set_server_common_status(common, SERVER_NOT_WORKING);
} else {
set_server_common_status(common, SERVER_NAME_RESOLVED);
}
/* Take care of all requests for this server. */
while ((request = common->request_list) != NULL) {
DLIST_REMOVE(common->request_list, request);
if (resolv_status) {
/* FIXME FIXME: resolv_status is an ARES error.
* but any caller will expect classic error codes.
* also the send() function may return ENOENT, so this mix
* IS explosive (ENOENT = 2 = ARES_EFORMER) */
tevent_req_error(request->req, resolv_status);
} else {
tevent_req_done(request->req);
}
}
}
int
fo_resolve_service_recv(struct tevent_req *req, struct fo_server **server)
{
struct resolve_service_state *state;
state = tevent_req_data(req, struct resolve_service_state);
/* always return the server if asked for, otherwise the caller
* cannot mark it as faulty in case we return an error */
if (server)
*server = state->server;
TEVENT_REQ_RETURN_ON_ERROR(req);
return EOK;
}
static void
set_server_common_status(struct server_common *common,
enum server_status status)
{
DEBUG(4, ("Marking server '%s' as '%s'\n", common->name,
str_server_status(status)));
common->server_status = status;
gettimeofday(&common->last_status_change, NULL);
}
void
fo_set_server_status(struct fo_server *server, enum server_status status)
{
if (server->common == NULL) {
DEBUG(1, ("Bug: Trying to set server status of a name-less server\n"));
return;
}
set_server_common_status(server->common, status);
}
void
fo_set_port_status(struct fo_server *server, enum port_status status)
{
DEBUG(4, ("Marking port %d of server '%s' as '%s'\n", server->port,
SERVER_NAME(server), str_port_status(status)));
server->port_status = status;
gettimeofday(&server->last_status_change, NULL);
if (status == PORT_WORKING) {
fo_set_server_status(server, SERVER_WORKING);
server->service->active_server = server;
}
}
void *
fo_get_server_user_data(struct fo_server *server)
{
return server->user_data;
}
int
fo_get_server_port(struct fo_server *server)
{
return server->port;
}
const char *fo_get_server_name(struct fo_server *server)
{
return server->common->name;
}
struct hostent *
fo_get_server_hostent(struct fo_server *server)
{
if (server->common == NULL) {
DEBUG(1, ("Bug: Trying to get hostent from a name-less server\n"));
return NULL;
}
return server->common->hostent;
}
|